The present invention relates generally to an apparatus and method for hardening metal by varying the engagement between irradiation and the metal.
Data on the useful application of radiation on metal is nearly non-existent. Some prior art publications describe the useful application of high-dose electron beam radiation on tungsten carbide and other hard metals. As seen in FIG. 2, this prior used an electron beam generator to both irradiate and heat the metal. The prior art required a continuous electron beam irradiating a stationary metal sample for an extended period of time. As a result, the prior art failed to efficiently and effectively maintain conditions conducive to the facilitation of the morphological changes in the metal.
The prior art fails produce a useful commercial product because the yield is low and is uneconomical for most industrial applications. The prior art used a continuous stream of 1.4 MeV electrons to irradiate stationary metal samples kept in a melting medium or xe2x80x9cgatexe2x80x9d. A single surface of the metal sample faced the irradiation during the prior art process. The electrons were largely stopped in the gate material and never reached the metal sample. Most of the electron radiation failed to reach the sample because normally 1.4 MeV electrons penetrate to only an approximate depth of only 2.6 mm in a typical oxide gate with a density of 2.7 g/cc. As a result, almost no electron radiation reached the metal sample and the limited amount that does only penetrates to a depth of less than a micron into the surface of the metal sample directly facing the irradiation.
Also, the prior failed to reposition the electron beam or the metal sample to effectively irradiate the entire metal sample. As the small percentage of irradiation pass through the gate material and engaged the metal sample, the irradiation continuously struck only the single surface initially exposed to the irradiation. The prior art failed to appreciate the increase hardening possible through the variance of the engagement location between the irradiation and the metal sample.
Variance in the positioning of the metal sample relative to the irradiation allows a deeper penetration of the irradiation into the numerous surfaces of the metal sample. This increases the hardening characteristic of the metal after irradiation.
Other minute amounts of radiation from the electron beam may have reached the metal sample. It is well known in the art that an energy beam creates x-rays when the energy beam strikes a solid object releasing photons.
Since the electron beams in the prior art are stopped in the oxide gate, less than one tenth of one percent of the electron radiation could be converted into x-rays, which could penetrate the melted oxide gate and reach the metal sample. This percentage is extreme low and practically insignificant in the irradiation of the metal.
Thus, there is a need for an apparatus and method that effectively, economically, and efficiently hardens metal through irradiation.
The present invention provides an apparatus for hardening a metal article, comprising a holding device, an energy beam generator pointed at the holding device for directing energy beams at the holding device, and a movement system supporting the holding device, wherein the movement system varies the orientation of the metal article relative to the energy beam generator. The apparatus includes an energy beam delivery instrument system positioned between the energy beam generator and the holding device so that the energy an energy beam delivery instrument directs the energy beam to the holding device. Also, the apparatus includes an auxiliary heating device engaging the holding device, wherein the auxiliary heating device heats the metal article independently from the energy beam.
A method for hardening metal is also disclosed. This method includes irradiating the metal, heating the metal independently from the irradiation, and varying the engagement location of the irradiation and the metal article. The method teaches separating the metal from the atmosphere using a fluid material, redirecting the irradiation as it approaches the metal, and manipulating the position of the metal during the irradiation.
A main purpose of this invention is to effectively, economically, and efficiently harden metal by irradiating the metal article with an energy beam. This purpose requires heating and irradiating the metal sample with predetermined amounts of irradiation at a predetermined temperature to foster the metallurgical changes within the metal sample.
Irradiation of the metal samples causes a reduction in the porosity of the metal surface. Also, the irradiation creates a monolithic surface structure where the components of the metal sample, tungsten carbide and a cobalt binder, are converted into new phases. These two phenomenons facilitate increase in the wear characteristic of the metal sample.
It is therefore a general objective of the present invention to provide an apparatus for hardening metal using irradiation.
Another objective of the present invention is to harden metal with irradiation by varying the orientation of the metal relative to the irradiation.
Another objective of the present invention is to harden metal with irradiation by varying the engagement of the irradiation and the metal.
Still another objective of the present invention is to provide an apparatus for hardening metal using irradiation and heat independent from the irradiation.
Still another objective of this invention is to harden metal by purposefully converting an energy beam into x-rays in order to increase the amount of radiation reaching the metal.
Yet another objective of the present invention is the use of gamma rays to harden metal.
Another object of the present invention is to reduce the amount of irradiation needed to harden metal by using higher energy irradiation.
Still yet another objective of the present invention is to harden tungsten carbide through irradiation.
Numerous other objects, features and advantages of the present invention will be readily apparent to those skilled in the art, upon the reading of the following disclosure, when taken in conjunction with the new drawings.